Dynamic pressure testing of articles, for example, pressure transducers for use in various applications is well known. Dynamic pressure testing is typically used to test the longevity of an article, e.g., a pressure transducer when subjected to a plurality of time dependent cycles. Many and different types of dynamic pressure testing apparatus have been utilized. For example, shock tube testing provides two sections of a tubing separated by a thin diaphragm. When a differential pressure is applied to the tube sections and the diaphragm ruptures, a resulting pressure shock occurs. Disadvantages of shock tube dynamic pressure testing include a complexity of and difficulty for setting up the test, is limited to one cycle only, cannot use liquid fluid media during testing and the shock wave raises the gas temperature. Shockless pressure step generators use a quick opening valve to generate dynamic pressure pulses. Generators of this type, however, are limited mechanically by the opening of the valve and are unable to reach high frequency pulses, i.e., cycles per second. Pulse generators typically employ a mass dropped onto a piston in contact with an incompressible fluid contained within a fixed volume. Generators of this type, however, are limited to single step response, i.e., one cycle. There are also shaker base systems which utilize a liquid filled tube mounted on an armature of a shaker to produce dynamic pressure. Shaker base systems, however, are generally cumbersome, require heavy duty shakers for large pressure displacements, and have their own governing maximum operating temperatures.
Pistonphones utilize a piston-in-cylinder to produce a sinusoidal pressure variation. While devices of this type are typically used with acoustic sensors such as microphones, pistonphones are limited to low frequencies and amplitudes. Finally, servo-valves generally use hydraulic systems to control dynamic components. Pressure is generated by an external pump and is dynamically controlled by applying a biased alternating signal to the servo-valve. This signal moves a mechanical member inside the servo-valve, in turn directing working fluid through various ports and controlling a shuttle valve. The end result is a dynamic pressure signal at the output.
Oftentimes, these dynamic pressure systems cannot meet amplitude and frequency requirements for many applications. Further, many articles are subjected to caustic or corrosive fluids in use. The combined stresses caused by the caustic or corrosive fluids as well as the pressure variations to which the article is subjected in use are stresses not typically accounted for in prior dynamic pressure testing systems. There is also a need in certain applications for a very substantial number of pressure cycles in a short period of time, e.g., one billion cycles in 40 days or less, to insure the adequacy of the dynamic pressure testing.